Corn choppers provided with multirow cornstalk-cutting heads are known wherein a channel leading to a chopper blade or a conveyor (feeding, in turn, a chopper blade) runs rearwardly from the leading edge of the machine, at which a sickle bar or other blade system cuts the stalk from the ground. On both sides of this channel, there are provided chains with entraining members which are disposed in several superposed planes and are intended to grip the cornstalks and displace them along the channel. The disadvantages of this system are that it is difficult to maintain the proper spacing of the chains, that considerable maintenance is required, and that considerable wear occurs which requires the chains to be replaced, retensioned and readjusted frequently.
Other cornstalk cutters have been provided in which a chain lies only along one side of the channel and the other side of each channel is provided with flexible pressing bars which retain the stalks against the protuberances of the conveyor chain. In such systems the frictional resistance to advance of the chain is high and there is often a nonuniform or uncontrolled stalk advance which becomes discontinuous, leading to blocking of the channel.
A further disadvantage of the conventional cornstalk cutting heads (corn heads) is that the channels widen toward the chopping unit. In some agricultural machines of this type, a transverse worm conveyor is provided between the corn head and the chopping unit and the crop material is gathered from the corn head displaced over a constricted cross-section to the chopping unit. In such devices, the orientation of the stalks reaching the cutting unit is indeterminate and an optimum or accurate chopping is not obtained.
In earlier corn heads, moreover, the material throughput is limited and, when large throughputs are attempted, the stress on the chains and sprocket wheels become nonuniform, leading to increased wear. These disadvantages have placed limits on the size of the corn heads to the extent that they have not hitherto been developed for high harvesting rates, i.e. for many crop rows.